Catalyst therefor



Reissues! Aug. 21, 1934 'v Re. 19,282

oxma'rrorz or .sULrmm nroxm AND cA'rALYsr 'rncaaroa Frans Slama, deceased,

on the Rhine,

late of Lndwinhafen- .by the General Chemical Company, New York, N. Y., asslgnee, and Hans Wolf, LudwIgshafen-on-the-Rhinc, Germany; said Slama-and said Wolf assignors to General Chemical Com N. Y., a corporation of New York Original at.

No Drawing.

, New York,

1,311,004, dated March 8, 1921, Serial No. 885,807, October 9,

1914. Application for reissue June 16, 1934,

8 Claims. (Cl. 23-415) This invention relates to the productionand use oi a commercially 'efiicient catalyst or contact substance for the production of sulphuric anhydrid from sulphur dioxid and oxygen.

In United States Patent No. 087,834, is de-- scribed a substance of the general class of vanadium catalyists: however, the product of that patent does not convert more than 84% of the sulphur dioxid into sulphuric anhydrid, which 10 makes it useless for commercial purposes.

Now, the above named applicants discovered a new vanadium catalyst which efl'ects conversion of sulphur dioxid and oxygen into sulphuric anhydrid to an extent of 96% and over of the contained sulphur dioxid. Broadly considered, this invention consists in providing a carrier for a vanadium containing substance, which carrier has a fineness of division very much greater than that of similar carriers heretofore employed. Prior to the invention of these applicants no vanadium catalysts had been used or described in which the carrier was less than 5000 microns in maximum dimension. As such carriers there have been used ll ground pumice, kieselguhr, precipitated $111010 acid, stannic oxid, or stannic hidroxid, or mix-' tures of all or any of them: it is preferred to employ these materials of a degree of fineness such that the individual particles do not exceed twenty microns and are preferably in the neighborhood of one micron in diameter, although the invention is not limited to degrees of fineness fall lug-within such'limits, as coarser particles of carrier may be used and a large increase of conversion still be obtained. The reference in the claims to a carrier very finely divided is meant to indicate a carrier in the here defined finely divided form, that is to say so'much finer than those hitherto employed for vanadium catalysts that the catalyst of which it forms a part produces or is suited to produce, a commercially substantial increase of conversion dver those hitherto known: but not so coarse that it is not capable of granulatio Particles of carrier should, therefore, not have a diameter larger than sixty microns. I

In developing this feature of the invention several collateral or subsidiary new steps in the production of a suitable vanadium catalyst were discovered; for example, the addition of potasslum hydrate or sodium hydrate, or the carbonate 'or the sulphate or the nitrate of these, in order to protect the new catalyst from deteriorating in catalytic activity; finally, the removal of hygroscopic properties by heating such catalyst 5 in the presence of air and in the absence of sulphur dioxid.

The vanadium may be used in. the form of vanadic oxid or of ammonium vanadate, or of potassium vanadate, with or without, as the case so may be, the addition of potassium or sodium l hydrate, carbonate, sulphate, or nitrate, so as to stabilize the catalyst by overcoming any hygroscopic properties which it may possess.

It is possible, and in fact likely, that the potassium or sodium hydrate may lose its water upon heating and bepresent in the catalyst in the form of potash or soda. The reference in the claims to potash is intended to cover potassium oxid and potassium hydrate, as the case may be, as well 7 as the other equivalent substances referred to.

This new catalytic substance, however prepared, may, if occasion requires, be commingled with a suitable binding agent and then molded or pressed into any desired shape. The substance may then be treated for some time in gases containing sulphur dioxid, for instance in burner gases, since this has a binding eifect upon the small particles and assists in rendering the catalyst more stable. Should the catalyst, after being heated by sulphur dioxid gases, be hygroscopic, this property can be diminished or re moved by subsequently heating it in the presence of air and in the absence of sulphur dioxid.

The following examples illustrate how this invention can be carried into effect, but it is 'to be distinctly understood as not being limited to the precise conditions therein set out, since these may be varied within considerable limits without departing from the spirit or this invention while obtaining the full benefit and value of this inventioi The parts are by weight:

Example 1:--Mix 200-parts of moist pumice powder (the grains of which have a diameter of one micron) with 14 parts of ammonium vanadate; 'granulate this mixture and heat the re-, sulting granular product to about 300 C. in thepresence of air until ammonia is no longer given on, and then heat to 440 C. in the presence of gas containing or consisting of sulphur dioxid, 109

until substantially no further change in the condition of the particles takes place. This product is now ready for use as a catalyst in the production of sulphuric anhydrid from gases containing sulphur dioxid and oxygen in the usual contact or catalytic process. Any other suitable carrier may be used in place of the pumice if in sufficiently finely divided condition.

Example 2:Mi-x 316 parts of kieselguhr (either as it occurs in nature or after trituration) which may previously have been heated to a red heat, with an aqueous solution of 50 parts ammonium vanadate and 56 parts of potassium hydrate; thereupon evaporate off so much of the water that the remainder can be formed into granules; place this result in a furnace and heat at 480 C. with gas containing sulphur dioxid and oxygen (such as can be obtained from a pyrites burner) and then, if desired, continue the heating for some time in a current of air; the product of this operation is a catalytic agent which is ready for use in the same manner as the product in Example 1.

The catalyst produced by Examples 1 and 2 is employed for the manufacture of sulphuric anhydrid in the usual manner, namely, by bringing into contact with it both sulphur dioxid and oxygen.

What is claimed is,

1. As a new composition of matter, a catalytic agent containing vanadium in chemical combination distributed on a very finely divided carrier not exceeding sixty microns in diameter.

2. As a new composition of matter, a shaped catalytic agent containing vanadium inchemical combination distributed on a very finely divided carrier not exceeding'sixty microns in diameter.

3. As a new composition of matter, a catalytic agent containing vanadic oxid distributed on a very finely divided carrier not exceeding sixty microns in diameter.

4. As a new composition of matter, a catalytic agent containing vanadic 'oxid and potash distributed on-a very finely divided carrer not exceeding sixty microns in diameter.

5. The improvement in the art of making sulphuric anhydrid which consists in causing sulphur dioxid and oxygen to come into contact with a catalytic agent comprising vanadium in chemical combination distributed on a very finely divided carrier not exceeding sixty microns in diameter.

6. The improvement in the art of making sulphuric anhydrid which consists incausing sulphur dioxid and oxygen to come into contact with a catalytic agent comprising vanadic oxid distributed on a very finely divided carrier not exceeding sixty microns in diameter.

7. The improvement in the art of making sulphuric anhydrid which consists in causing sulphur finely divided carrier not exceeding sixty microns m in diameter with a salt or vanadic acid and then heatingthe same in the presence of air and in the absence oi sulphur dioxid. I HANS WOLF.

THE GENERAL CHEMICAL COMPANY, Assignee of Franz Slama, Deceased, By F. H. NICHOLS,

a Vice President. 

